This invention generally relates to a magnetic bubble memory device and, more particularly, to a portable cassette type magnetic bubble memory device which can be smoothly loaded and unloaded.
A typical magnetic bubble memory apparatus has a construction as shown in the block diagram of FIG. 1, comprising a peripheral circuit section 9 and a central processing unit (CPU) 12 connected thereto, wherein the circuit section 9 includes an interface control circuit 1, a magnetic bubble memory device control circuit 2, a timing control circuit 3, a magnetic bubble memory device drive circuit 4, a magnetic bubble memory device 5, a signal detection circuit 6, a rotating magnetic field drive circuit 7 and a pulse current drive circuit 8, and the central processing unit (CPU) 12 includes a microprocessor 10 and a random access memory (RAM) 11. The magnetic bubble memory device 5 has, as well known in the art, a magnetic bubble memory element, a pair of permanent magnet plates for generation of a bias field, yokes therefor and a pair of coils for generation of a rotating field, and its data write and read operations are controlled by commands from the CPU 12.
With the recent spread of the magnetic bubble memory apparatus noted above, there is an increasing need for a cassette type magnetic bubble memory device which is advantageous from the standpoint of cost reduction, portability and ease of operation. In a cassette type magnetic bubble memory device, a cassette including the magnetic bubble memory device 5 is inserted into a loader including circuit components of section 9 except for the magnetic bubble memory device 5.
As the above cassette type magnetic bubble memory device, there has been proposed one as shown in FIG. 2. This construction comprises a case 13, for instance made of synthetic resin, accommodating a magnetic bubble memory device 5 mounted on a base plate 14, the case having an end provided with a connector 15 for connection to a loader.
The cassette type magnetic bubble memory device having the above construction, however, has the following drawback. Since the outer frame of the cassette type magnetic bubble memory device shown in FIG. 2 is constituted by the synthetic resin case 13, its mechanical strength against shocks is low. In addition, since a large space filled with air is present in the case 13, the thermal resistance from a heat-generating element in the cassette to air outside the case 13 is high and, therefore, the heat radiation property is poor. The operating characteristics of the cassette type magnetic bubble memory device thus are greatly deteriorated when the cassette is in a high-temperature atmosphere. Further, the size of the connector 15 is so large that the thickness of the cassette amounts to about 20 mm. Therefore, the cassette has difficulties with portability and cost reduction. Moreover, since the electric signal pins of the connector 15 are embedded in an insulator of synthetic resin, the electric circuit inside the cassette is liable to be destroyed by discharge of electrostatic charge only through the pins.